Large machines, such as dozers, scrapers, excavators, etc., use implements to perform various work functions. Accurately positioning an implement, for example, the depth of a ripper or blade, may be important to the accurate preparation of a worksite for subsequent activity, including mining or construction. Cylinder position sensors using magnetostrictive technology can give accurate measurements of implement position but can be expensive and may require each cylinder rod to be gun bored so that wiring and magnetic sensors can be mounted inside. In addition to the cost, these sensors can be difficult to calibrate and maintain in a construction or excavation environment. An inertial measurement unit (IMU) can give a relatively accurate position in an ideal environment but are susceptible to noise when used with heavy equipment. Some implements, such as a dozer blade on arms, do not swing a large enough arc to use a rotary sensor for accurate measurements of arm angle.
With respect to implement position sensors, U.S. Pat. No. 8,620,534, issued Dec. 31, 2013 to Jessen (the '534 patent), discloses sensing the position of an implement by first developing a static position using an inclination sensor and subsequently using an estimated cylinder travel to arrive at an estimated new position. However, the '534 patent fails to account for other movement of the machine or inaccuracies associated with cylinder position estimation.